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PGA460: Tx does not work properly in all my boards

GL Wang
Prodigy 20 points
Part Number: PGA460

Hello, I have a big problem with PGA460 and need confirmation/suggestions from expert.

  1. I have 4 development boards from a non-TI supplier. My host MCU is Arduino 33 nano BLE board, and the interface I used is asynchronized UART. The baud rate is 9600.  Now, PGA460 Tx signal (Without a pull-up resistor) on the 4 boards becomes weird as it passes a high-pass filter, see the attached oscilloscope plot.  I changed the Pull-up resistor from 3.3k, to 560k to infinity (non), it only changes the average level of the Tx but NOT the amplitude.
  2. The board has a pull-up resistor on the pin “test”. I de-solder them myself, since my system is 3.3v.
  3. The 1st board does not work from the first moment even with a 3.3k pull-up to V3.3 on the Tx pin, and I concluded that it is a “bad” one from the retailer.
  4. The 2, 3 and 4 boards worked right individually for some days, with a 3.3k pull-up to V3.3 on the Tx pin
  5. I burned the EEPROM of 2-3-4 boards to change their address as 0x00, 0x01 and 0x02, respectively.  And then connected them in a system with 3-Tx and 3-Rx connected together, with a 3.3k pull-up resistor. All worked in B-L mode but 2 of them had No. of Burst as zero. It did not work well as I expected.
  6. I then remove all boards from the system and tried to find the reason. During this process, I found ALL the TX is like the attachment. Non works now. I changed the Pull-up resistor from 3.3k, to 560k to infinity (non), it only changes the average level of the Tx but NOT the amplitude. Possible mistake I might made is: wrongly interchanged Rx/Tx of PGA460 to the host MCU for some minutes.

Now, my question is

  1. Are all all my PGA460 damaged OR locked in some way?  is this related to " burn an eeprom"? Any ways to solve the problem?
  2. If I order new boards, what should I do to avoid this?

Thanks  for your answers in advance!  

  • 0
    TI__Mastermind 21410 points

    Hey GL,

    Thanks for posting on the sensing forum and for your interest in PGA460! Sorry to hear you are encountering some issues during development. Just a quick questions is this test on a custom board or are you using any of the available EVMs? (BOOSTXL-PGA460, PGA460PSM EVM)

    It sounds like this may have been performed on a custom test board and if this is the case could you please provide some schematics to better understand your comments that would be extremely helpful.

    As far as the comments you made about change the TEST pin pullup resistor this is only to change the digital output from 3.3V to 5V and this should not much of an affect on the TX output.

    1. EEPROM is just used to store registers from the system but I do not believe if it is possible to lock the device and have no communication with it. 

    2. Typically we suggest ordering one of our EVMs along with the accompanying microcontroller in order to help you get familiar with the PGA460. This device has a lot of features so it can be a little difficult to navigate for the first time especially on customer hardware. The GUI and our training videos really help in making the device more intuitive when working with it.

    Looking forward to your response!

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    Prodigy 20 points

    Hello, Isaac

    Sorry for the late reply!

    My problem is solved. I gave an address to my sensor each. The addresses burn in the EEPROM are not the intended "right" ones, and therefore no sensor listened to the program. The TX signal posted above is the "cross talk" from Rx, as someone said in this forum before.

    Best 

    GL 

  • 0 in reply to GL Wang
    TI__Mastermind 21410 points

    Hello GL,

    Thanks for the update glad to hear that your issue was resolved!

    Best,

    Isaac